An RTM method, in which a preform formed from a reinforcing fiber substrate is placed in a cavity of a molding die, and resin is injected from a plurality of injection ports into the cavity and impregnated into the preform, is well known. For example, in JP-A-2005-246902, a method wherein resin is injected simultaneously from a plurality of injection ports disposed inside a product area of an article to be molded relative to a fiber reinforcing substrate placed in a cavity, a so-called “multi-point” injection method, is disclosed. Further, in JP-A-2007-144994, a molding method, wherein seal portions that control resin flow are provided on both sides of the direction in which resin flows and resin is injected from the side of the periphery part of a cavity, is disclosed.
In the above-described multi-point injection method such as disclosed in JP '902, for example, as shown in FIG. 1(A), although resin (shown by arrows) is injected from a plurality of injection ports 3 disposed within an area of a product line 2 of an article to be finally molded relatively into a preform formed from a reinforcing fiber substrate, there is a problem that it requires a relatively long time for the distribution of the resin from the respective injection ports 3 to the whole of the preform 1 and the resin impregnation is slow. Further, in the method such as disclosed in JP '994 in which resin is injected from the side of the periphery part of a cavity, for example, as shown in FIG. 1(B), although resin (shown by arrows) is injected into the preform 1 from injection ports 4 disposed at the side of the periphery part of the preform 1, there is also a problem that it requires a relatively long time for the distribution of the resin from the respective injection ports 4 to the whole of the preform 1 and the resin impregnation is slow.
To solve the problems in the methods shown in FIGS. 1(A) and 1(B), although it is considered to combine the both methods, for example, as shown in FIG. 1(C), by merely combining them, the resin impregnation into the preform 1 becomes faster, but there is a possibility that a sink mark accompanying curing of the resin may occur at a section 5 located within the area of the product line 2 of an article to be finally molded, in particular, at a section at which the resin flow from the injection port 3 and the resin flow from the injection port 4 collide with each other and the like, and there is a fear that such a sink mark may damage the quality of the molded article. Further, by merely combining both methods, with respect to resin flow to improve resin impregnation into a molded product, a resin flow positively utilizing the periphery-side part cannot be realized, rather in JP '994, a seal portion is provided to obstruct the positive flow along the periphery.
Further, in JP-A-2003-71856, although an RTM method indicating a temperature during molding as a parameter is shown, an attempt to positively control a temperature distribution in a die is not described. Namely, it does not positively provide resin impregnation at a high velocity, and it also does not simultaneously address resin impregnation at a high velocity with an improvement in quality of a molded article.
Accordingly, there is a need for resin impregnation at a high velocity with simultaneous improvement in quality of a molded article that has not been achieved in conventional technologies to an RTM method that injects resin from a plurality of injection ports.